Decolorization of petrolatum stocks



Patented July 19, 1949 DECOLORIZATION F PETROLATUM STOCKS William McPheeters Jarnagin, Philadelphia, Pa.,

assignor to Attapulgus Clay Company, Philadelphia, Pa., a corporation of Delaware N 0 Drawing. Application. February 21, 194?,

Serial No. 730,197

4 Claims. (01. 196-431) The present invention relates to a method for improving the yield of decolorized petrolatum by preliminary oxidation of petrolatum stock followed by treatment with a decolorizing adsorbent.

In accordance with the present invention, a crude petrolatum stock is contacted with air or other free oxygen-containing gas at an elevated temperature between 250 F. and 400 F., and preferably at about 300 F. for a period of time sufiicient to obtain partial oxidation, for example, to 3 or 4 hours, and the resulting product is cooled and filtered through a. granular decolorizing adsorbent at a temperature suflicient to maintain the product in a fluid state, for example, 180 F. to 220 F. The decolorizing adsorbents include thermally activated bauxite, fullers earth, acid treated bentonite, extruded fullers earth, synthetic calcium silicate, magnesium silicate, aluminum silicate, or the like. Bauxite and fullers earth may be thermally activated at 700 F. to 1200 F., while the other adsorbents may simply be dried at 250 F. to 400 F, prior to use. The length of the oxidation period depends upon the temperature, the efiiciency of contacting, and the amount of air used, such period being inversely proportional to the temperature and the amount of air. For example, a temperature of 250 F. may be employed with a relatively large amount of air injected over a long period, whereas a higher temperature such as 300 F. to 400 F. may be employed with a smaller amount of air over a shorter period. However, the time-temperature-air relationship must be determined for the various petrolatum stocks, since there will be some difference in response depending upon the source of the stock, its composition, and prior treatment, if any.

The crude petrolatum stocks which may be decolorized in accordance with the present invention can be obtained from petroleum by various methods. For example, a Pennsylvania crude oil may be topped by distillation and the residue, after dilution with naphtha, may be settled or centrifuged at low temperature, whereby a substantial proportion of the oil content of the residue is removed, thus leaving a crude petrolatum stock. Or, a heavy distill-ate fraction from a waxy crude oil may be solvent deoiled by adding a solvent such as acetone-benzol, methyl ethyl ketone, liquid propane, or other conventional solvent, the mixture then cooled, and the solvent containing dissolved oil removed from the waxy residue constituting the petrolatum stock. Such stock may have a residual oil content of from to 50% depending upon the efiiciency of the deoiling treatment, the wax in such stock being of the mlcrocrystalline type. Crude petrolatum stocks may also be obtained from crude petroleum containing asphaltic constituents by distilling ofi the lighter fractions and treating the residuum with liquid propane or other agent to precipitate the asphaltic constituents. After removal of the asphalt, the residuum may then be deoiled with solvents as mentioned above.

The present invention may be further illustrated by the following examples, which, however, are not to be construed as limiting the scope thereof.

1000 m1. portions of crude petrolatum derived from Pennsylvania crude oil were heated at 300 F. for hour and blown with air at a rate of 6 and 15 liters per hour, respectively. The air blown petrolatum stocks were then filtered through 350 gram beds 20-60 mesh bauxite at 210 F. at a rate of 0.5 ml. per minute to a color of /g A. S. T. M., the bauxite having been thermally activated at 1200 F. before use. The yields at this color are given in the following table, as well as the yield of the same stock which had not been contacted with air at elevated temperature.

Oxidation Air- Yield ml./l00 sample liters/hour grams bauxite none 15.8 6 25. 4 15 26.5

From the above data, it will be seen that a marked improvement in yield is obtained by preliminary treatment with air at elevated temperature, followed by decolorization with a solid adsorbent. While it is preferred to employ the percolation technique with granular bauxite or fullers earth, decolorization may also be effected by dispersing the solid adsorbent as a powder in the oxidized stock at elevated temperature, and then removing the adsorbent by filterpressing upon completion of the decolorization. The adsorbents may be regenerated, if desired, by steaming or solvent treatment, followed by drying or thermal activation, when the decolorizing power of the adsorbent has decreased to an uneconomic level through adsorption of color bodies or other carbonaceous materials.

I claim:

1. A method for decolorizing petrolatum stock, which comprises contacting said stock with air at a temperature between 250 F. and 400 F. for /g to 4 hours, and thereafter contacting the oxidized stock with a decolorizing adsorbent at a temperature such that the oxidizing stock is in a fluid state.

2. A method for decolorizing petrolatum stock, which comprises contacting said stock with air at a temperature between 250 F. and 400 F. for /2 to 4 hours, and thereafter contacting the oxidized stock with a decolorizing adsorbent at a temperature between 180 F. and 220 F.

3. A method for decolorizing petrolatum stock, which comprises contacting said stock with air at a temperature between 250 F. and 400 F. for to 4 hours, and thereafter contacting the oxidized stock with thermally activated bauxite at a temperature between 180 F. and 220F.

4. A method for decolorizingrpetrolatum stock,

which comprises contacting said stock with air at a temperature of about 300 F. for about hour, and thereafter filtering the oxidized stock ,4 through thermally activated bauxite at a temperature of about 210 F.

WILLIAM MCPHEETERS JARNAGIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Stossel July 29, 1947 

